docs: def get_request_headers(self):
          """Return request headers that will be sent to upstream.
  
          The header REMOTE_USER is set to the current user
          if AuthenticationMiddleware is enabled and
          the view's add_remote_user property is True.
  
          .. versionadded:: 0.9.8
  
          """
          request_headers = self.get_proxy_request_headers(self.request)
  
          if (self.add_remote_user and hasattr(self.request, 'user')
                  and self.request.user.is_active):
              request_headers['REMOTE_USER'] = self.request.user.get_username()
              self.log.info("REMOTE_USER set")
  
          return request_headers